> By your reasoning, if I was to put a camera in a tumble-dryer and let it snap photos while spinning, those photos would not be mine because whilst I set up the circumstances, the actual photos were not specifically composed by me.

I don't have a problem with that consequence. Copyright is supposed to reward creativity. I don't consider "photo made by putting camera into a tumble dryer" creative in any meaningful sense. I understand that a lot of modern performance art would probably be excluded with this approach - but I don't see it as a problem, either.